EP0627615A1 - Füllstandsmessystem - Google Patents
Füllstandsmessystem Download PDFInfo
- Publication number
- EP0627615A1 EP0627615A1 EP94302877A EP94302877A EP0627615A1 EP 0627615 A1 EP0627615 A1 EP 0627615A1 EP 94302877 A EP94302877 A EP 94302877A EP 94302877 A EP94302877 A EP 94302877A EP 0627615 A1 EP0627615 A1 EP 0627615A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- signal
- impedance
- analogue
- fluid
- sensors
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
- G01F23/243—Schematic arrangements of probes combined with measuring circuits
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
Definitions
- This invention relates to fluid level sensing systems, and is more particularly but not exclusively concerned with boiler water level sensing systems of the general kind disclosed in United Kingdom Patents Nos 1 056 032 and 1 438 271.
- Boiler water level sensing systems of the kind described in United Kingdom Patents Nos 1 056 032 and 1 438 271 typically comprise a vertically extending cylindrical pressure vessel, sometimes called a "water column", adapted to be connected near its top and near its bottom to one end of a boiler, such that the water level in the pressure vessel is substantially the same as the water level in the boiler.
- a plurality of vertically spaced electrodes sealingly project into the pressure vessel, and are used to sense the electrical impedance of the fluid in the pressure vessel at the respective level of each electrode. Since the minimum electrical impedance of steam is significantly greater than the maximum electrical impedance of water, the position of the water/steam interface can readily be established.
- Systems of this kind are currently commercialised by the Applicant under the trade mark HYDRASTEP.
- a fluid level sensing system for sensing the level of the interface between a first fluid and a second fluid, the first fluid being beneath and of lower electrical impedance than the second fluid
- the system comprising an electrically conductive vessel for containing the fluids and a plurality of vertically spaced sensors each of which has a sensing portion which projects into and is electrically insulated from the vessel and which is arranged, in use, to produce a signal representative of the impedance of the fluid between the sensing portion and the vessel, further comprising output means responsive to said impedance-representative signals for producing a first signal which is dependent upon the ratio between the impedance sensed by the sensor at or immediately below said interface and a value for the impedance of the first fluid derived from at least one sensor below the sensor at or immediately below said interface, and for combining said first signal with a second signal dependent upon the level of the sensor at or immediately below said interface so as to produce an output signal representative of the level of said interface within the vessel.
- the system effectively interpolates between adjacent sensors using the changing impedance sensed by the sensor at the interface as the interface rises to progressively immerse the sensing portion of that sensor in the first fluid and then rises further to progressively increase the area of the path in the first fluid between the sensing portion of that sensor and the vessel.
- This interpolation is compensated for variations in the impedance of the first fluid by using as a reference a value for the impedance of the first fluid derived from the impedance sensed by at least one sensor below the interface sensor, ie a sensor which is totally immersed in the first fluid.
- this reference is derived by extrapolation from several totally immersed sensors, ideally the ones immediately beneath the interface sensor.
- the system comprises a respective reference impedance for each sensor, and at least one reference signal source for applying an AC reference signal via each reference impedance to the sensing portion of the sensor associated with that reference impedance, whereby the reference impedance and the fluid between the sensing portion of the associated sensor and the vessel form a potential divider.
- the output means preferably comprises at least one analogue-to-digital converter for converting the impedance-representative signal derived from the sensor at or immediately below said interface into a corresponding digital signal, and a microprocessor arranged to receive the digital signal and to produce said first signal therefrom.
- the system may comprise a respective analogue-to-digital converter associated with each of said sensors.
- the system may comprise one analogue-to-digital converter and multiplexing means for multiplexing the analogue-to-digital converter between the sensors on a time multiplexed basis, or two analogue-to-digital converters, first multiplexing means for multiplexing one analogue-to-digital converter between the sensors of a first group of sensors on a time multiplexed basis, and second multiplexing means for multiplexing the other analogue-to-digital converter between the remaining sensors on a time multiplexed basis, the sensors of the first group comprising every alternate one of the vertically spaced sensors.
- the microprocessor is further arranged to produce said second signal and to sum it with said first signal, the resulting summed signal being applied to a digital-to-analogue converter so as to produce said output signal in analogue form.
- the reference impedances, the or each reference signal source, the or each analogue-to-digital converter, the or each microprocessor, the or each digital-to-analogue converter and the multiplexing means (if present) are preferably disposed in a housing remote from the sensors.
- the boiler water level sensing system shown in Figure 1 is indicated generally at 10, and comprises an elongate cylindrical steel pressure vessel 12 which in use is coupled to one end of a boiler 14 by upper and lower pipe couplings 16 adjacent the top and bottom respectively of the vessel, so that the water level in the vessel is substantially the same as the water level in the boiler.
- the couplings 16 typically include shut-off cocks and drain valves (not shown) to facilitate removal of the electrodes 18 from the pressure vessel 12 for maintenance and/or replacement.
- Each electrode 18 may be substantially as described in our United Kingdom Patent No 2 173 138, and as best seen in Figure 2 comprises a sensing portion or tip 22 electrically connected to a terminal 24 outside the pressure vessel 12 by means of a conductor 23 extending coaxially through the body 26 of the electrode.
- the sensing tip 22 and the coaxial conductor 23 are electrically isolated from the body 26 of the electrode by an annular space and an annular ceramic insulator 28, the latter also serving to secure the sensing tip to the body.
- the insulator 28 defines a sensing gap between the sensing tip 22 and the body 26 of the electrode 18 and the pressure vessel 12, which gap is bridged in use by the fluid (water or steam) inside the pressure vessel 12 at the level of the electrode. Since the minimum electrical impedance or resistance of steam is substantially greater than the maximum electrical impedance or resistance of water, sensing the electrical impedance of the fluid bridging the sensing gap of the electrode 18 provides an indication of whether the electrode is immersed in water or in steam.
- an alternating signal produced by an oscillator 30 is applied via a drive resistor 32 and a first wire 34 to the terminal 24 of the electrode 18.
- the oscillator 30 and the drive resistor 32 are disposed in a circuit housing or cabinet 36 which can be up to thirty metres away from the pressure vessel 12 and the boiler 14, since the immediate vicinity of the boiler represents a fairly harsh environment.
- a return or ground wire 38 connects the ground or zero volt power supply rail 40 of the oscillator 30 and the other circuitry in the cabinet 36 to the pressure vessel 12 and thus to the body 26 of the electrode 18.
- the drive resistor 32 and the impedance of the fluid bridging the sensing gap of the electrode 18 together form a voltage divider, so that the alternating voltage at the terminal 24 is representative of the fluid impedance at the sensing gap of the electrode 18.
- This alternating voltage is applied via a further wire 42 to a rectifying amplifier 44 in the cabinet 36.
- the rectifying amplifier 44 therefore produces a DC output voltage V whose amplitude is substantially proportional to the impedance sensed by the electrode 18, and this DC output signal is applied to one input of a first comparator 46.
- the other input of the comparator 46 is connected to receive a first reference voltage VR1, whose level is selected to lie about midway between the respective amplitudes of the DC output voltages produced by the rectifying amplifier 44 corresponding to the minimum sensed impedance of steam and to the maximum sensed impedance of water.
- a first reference voltage VR1 whose level is selected to lie about midway between the respective amplitudes of the DC output voltages produced by the rectifying amplifier 44 corresponding to the minimum sensed impedance of steam and to the maximum sensed impedance of water.
- Each of the twelve electrodes 18 is connected to its own channel of impedance measuring (or discrimination) circuitry comprising circuit elements identical to the elements 32, 34, 38, 42, 44 and 46: this discrimination circuitry is collectively indicated at 50 in Figure 1. Additionally, the electrodes 18 are normally divided into two vertically interleaved groups of six, ie containing odd and even numbered electrodes respectively, with each group having a respective common oscillator 30 and a respective common power supply (not shown): thus if one power supply or oscillator fails, the other group of electrodes and their discrimination circuitry 50 continue to operate to provide level sensing, albeit with reduced resolution.
- the comparators 46 within the discrimination circuitry 50 drive a display 52 comprising twelve pairs of adjacent, horizontally aligned, indicator lights, typically LEDs, arranged to form two parallel vertical rows, one red, representing steam, and one green, representing water.
- the output of each comparator 46 is connected to its green (water) light 54, and via an inverter 56 to its red (steam) light 58: typically these connections may include suitable drive amplifiers, but these have been omitted for the sake of simplicity.
- a typical normal indication provided by the display 52 would have the top six red lights on, and the bottom six green lights on, indicating that the water in the boiler 14 is at its normal level.
- the boiler water level sensing system 10 is provided with further fault detection circuitry which operates when the resistance sensed by an electrode 18 falls below a given level.
- the minimum resistance of water, as sensed by the electrode 18, is about 5 kilohms, so that a sensed resistance significantly lower than this is likely to be indicative of a fault.
- the DC output voltage V of each rectifying amplifier 44 is applied to one input of a respective second comparator 64, whose other input is connected to receive a second reference voltage VR2 selected to be equivalent to a sensed impedance of about 3 kilohms, as represented by the DC voltage produced by the rectifying amplifier 44.
- the comparator 64 thus produces a logic O output signal if its electrode 18 is immersed in water or steam, and a logic 1 output signal if the DC output signal produced by the rectifying amplifier 44 falls below VR2.
- the logic 1 output signals are operative, via respective OR gates 65 associated with the odd and even numbered electrode channels, to operate another fault indicator light 66 in the display 52.
- each sensing channel of the second comparator 64 in combination with the use of the respective wires 34, 42 to connect the drive resistor 32 to the terminal 24 of the electrode 18, and the terminal 24 back to the rectifying amplifier 44 (instead of using just a single wire between the terminal 24 and a common terminal in the cabinet 36 connected both to the drive resistor 32 and to the rectifying amplifier 44), has the result that several different faults are rendered detectable.
- each second comparator 64 will operate the fault indicator light 66 in the display 52 if either of its associated wires 34, 42 breaks or is short-circuited to ground (since both of these faults result in no output voltage from the rectifying amplifier 44), or if the sensing gap of an electrode 18 is short-circuited, eg by a build-up of an electrically conductive deposit on the ceramic insulator 28 (which again results in no output voltage from the rectifying amplifier 44).
- this wide range of fault detection is provided without requiring different wiring or circuit arrangements for steam-normal and water-normal electrodes, ie all twelve channels are substantially identical.
- relay logic can be used in place of electronic logic, and displays other than that specifically described can be used.
- each set of discrimination circuitry 50 can comprise a single channel of elements identical to the elements 44, 46 and 64, with a multiplexer at the input to the circuitry for sequentially connecting the input of the rectifying amplifier 44 to each of the associated electrodes in turn, ie on a time multiplexed basis; such multiplexers are indicated at 70 in Figure 1.
- a demultiplexer (not shown), synchronised with the multiplexer 70 and located within the display 52, connects the respective outputs of the comparators 46 and 64 to respective latches or other memory devices, also forming part of the display 52, which are arranged to operate the indicator lights 52, 58 of the display and to provide the aforementioned cross-coupled connections between the two sets of validation circuitry.
- the system 10 as described so far provides a relatively low resolution digital output signal suitable for driving the display 52.
- this signal is not always suitable for control purposes, eg for controlling a feedwater pump to maintain the level of the water in the boiler 14 substantially constant.
- a high resolution output signal is provided by circuitry indicated at 74 in Figure 1, and shown in more detail in Figure 3.
- the sensing gap defined by the insulator 28 of that electrode starts to be bridged by the water and the impedance sensed by that electrode starts to fall from its very high, steam, value.
- this fall in the sensed impedance continues (albeit non-linearly) as the given electrode 18 is progressively immersed in the water.
- the impedance sensed by it continues to fall (albeit more slowly) as the water rises towards the next electrode, since the rising water level increases the area of the path in the water from the sensing tip 22 of the just-immersed electrode to the pressure vessel 12 (which being directly electrically connected to the body 26 of every electrode 18 effectively forms the earth or zero volt reference of the entire system).
- This progressively changing sensed impedance is processed by the circuitry 74 of Figure 3, which comprises a dual input analogue-to-digital converter 80 arranged to successively receive as inputs the respective time multiplexed voltages produced by the rectifying amplifiers 44 for each electrode 18 in turn, and to convert them into corresponding digital signals: to this end, the analogue to digital converter 80 operates at twice the frequency of the multiplexers 70.
- the digital signals are applied to a microprocessor 82, which also receives as inputs the signals produced by the comparators 46 and the OR gates 65 in order to enable it to determine which electrodes 18 are fully immersed in water, which electrodes are fully in steam, and therefore which electrode is at or immediately beneath the interface between the water and the steam in the pressure vessel 12.
- the microprocessor 82 stores the respective digital signals derived from the electrode 18 at or immediately beneath the steam/water interface and several of the electrodes immediately beneath that electrode.
- the microprocessor 82 first calculates, by extrapolation from the respective signals derived from the several electrodes 18 immediately beneath the interface electrode, the impedance of the water at the level of the interface electrode (this calculation is effected because the impedance of the water can vary considerably, not only with boiler operating conditions such as temperature and pressure, but even with height within the pressure vessel 12), and then calculates the ratio between the impedance actually sensed at the interface electrode and this calculated water impedance.
- the microprocessor 82 effectively compares the value of this ratio with values previously stored in a look-up table (typically a ROM) and equating impedance ratio to the level above the bottom of the electrode 18 at or immediately beneath the steam/water interface, and produces a first signal representative of that level. Finally, the microprocessor 82 adds the first signal to a second signal representative of the level of the bottom of the electrode 18 at or immediately beneath the steam/water interface, to produce a digital output signal representative of the level of the steam/water interface. This digital output signal is applied to a digital-to-analogue converter 84, which converts it into a corresponding continously variable analogue signal at output 86, usable for control purposes.
- a look-up table typically a ROM
- the circuitry 74 of Figure 3 can typically interpolate between electrodes to a resolution of about 1mm, and provide an overall level measurement to an accuracy of about ⁇ 5mm.
- circuitry 74 is described as providing an analogue output signal via the digital-to-analogue converter 84, the digital output produced by the microprocessor 82 can be directly used instead if desired. Also, although the circuitry 74 is described as separate from and co-operating with both sets of circuitry 50, circuitry similar to the circuitry 74 can be alternatively or additionally incorporated in both sets of circuitry 50 to provide increased reliability.
Landscapes
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB939311187A GB9311187D0 (en) | 1993-05-29 | 1993-05-29 | Fluid level sensing systems |
GB9311187 | 1993-05-29 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0627615A1 true EP0627615A1 (de) | 1994-12-07 |
EP0627615B1 EP0627615B1 (de) | 2000-07-19 |
Family
ID=10736378
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94302877A Expired - Lifetime EP0627615B1 (de) | 1993-05-29 | 1994-04-22 | Füllstandsmessystem |
Country Status (8)
Country | Link |
---|---|
US (1) | US5553494A (de) |
EP (1) | EP0627615B1 (de) |
JP (1) | JPH06347307A (de) |
CA (1) | CA2124299C (de) |
DE (1) | DE69425301T2 (de) |
ES (1) | ES2148287T3 (de) |
GB (2) | GB9311187D0 (de) |
IN (1) | IN184470B (de) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1998006105A1 (en) * | 1996-08-01 | 1998-02-12 | Combustion Engineering, Inc. | Fluid level measuring instrument for a nuclear power plant |
EP0887628A1 (de) * | 1997-06-27 | 1998-12-30 | Solartron Group Limited | Sicherheitseinrichtung |
ES2124175A1 (es) * | 1996-10-04 | 1999-01-16 | Gaggia Espanola | Procedimiento para controlar el nivel de un deposito de suministro de agua y dispositivo para su puesta en practica. |
US8532244B2 (en) | 2007-06-14 | 2013-09-10 | General Electric Company | System and method for determining coolant level and flow velocity in a nuclear reactor |
Families Citing this family (21)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2288238B (en) * | 1994-04-07 | 1998-07-08 | Chromalock Ltd | Monitoring device for liquid levels |
US5541969A (en) * | 1994-08-24 | 1996-07-30 | Combustion Engineering, Inc. | Midloop water level monitor |
US5730026A (en) * | 1995-03-31 | 1998-03-24 | Josef Maatuk | Microprocessor-based liquid sensor and ice detector |
FR2735227B1 (fr) * | 1995-06-08 | 1997-08-14 | Europ Agence Spatiale | Procede de mesure de la quantite de carburant dans un reservoir d'un engin spatial tel qu'un satellite |
GB2354585B (en) * | 1999-09-27 | 2004-06-23 | Charis Technology Ltd | Apparatus for sensing the level of a conductive fluid |
US6546796B2 (en) | 2001-03-15 | 2003-04-15 | Therm-O-Disc, Incorporated | Liquid level sensor |
US7243540B2 (en) * | 2001-05-24 | 2007-07-17 | Potter Electric Signal Company | Low-water cut-off system |
US6904800B2 (en) * | 2001-05-24 | 2005-06-14 | Potter Electric Signal Company | Low-water cut-off system |
US6990861B2 (en) * | 2002-10-07 | 2006-01-31 | Ham Eric R | Stratified hot water heated depth display system |
US7219545B2 (en) | 2004-07-28 | 2007-05-22 | Vertex Pharmaceuticals, Inc. | Sensor for levels of conductive liquids |
TWI235520B (en) * | 2004-09-10 | 2005-07-01 | Antig Tech Co Ltd | Device for measuring fuel capacity in fuel cell system |
US7360418B2 (en) * | 2005-06-28 | 2008-04-22 | Keurig, Incorporated | Method and apparatus for sensing liquid level using baseline characteristic |
US20070146442A1 (en) * | 2005-11-14 | 2007-06-28 | Mydata Automation Ab | System, assembly and method for jetting viscous medium onto a substrate |
US7317993B2 (en) * | 2006-03-15 | 2008-01-08 | Potter Electric Signal Company | Fluid detector recognizing foam and surge conditions |
US8516650B2 (en) * | 2007-10-11 | 2013-08-27 | Black & Decker Inc. | Vacuum electronic water sense circuit |
JP2009281877A (ja) * | 2008-05-22 | 2009-12-03 | Hitachi High-Technologies Corp | 分注装置 |
US20100082271A1 (en) * | 2008-09-30 | 2010-04-01 | Mccann James D | Fluid level and concentration sensor |
US8903676B2 (en) * | 2010-07-12 | 2014-12-02 | Blake Jude Landry | Sensors, systems, and methods for measuring fluid perturbation |
US9677785B2 (en) | 2012-01-11 | 2017-06-13 | Rheem Manufacturing Company | Electronic water level sensing apparatus and associated methods |
JP6015391B2 (ja) * | 2012-11-30 | 2016-10-26 | 株式会社ノーリツ | 水位検出信号の検出装置 |
CN114645441B (zh) * | 2020-12-17 | 2023-09-19 | 广州视源电子科技股份有限公司 | 衣物护理机 |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1056032A (en) * | 1964-04-08 | 1967-01-25 | Central Electr Generat Board | Improvements in or relating to fluid indicating apparatus |
US3370466A (en) * | 1965-09-24 | 1968-02-27 | United States Steel Corp | Method and apparatus for locating interfaces between fluids |
US4020488A (en) * | 1972-05-10 | 1977-04-26 | Robert Edgar Martin | Alarm and/or control apparatus |
US4371790A (en) * | 1980-09-19 | 1983-02-01 | Rmr Systems, Inc. | Fluid measuring system |
EP0447810A2 (de) * | 1990-03-07 | 1991-09-25 | Hl Planartechnik Gmbh | Elektrische Messanordnung zur Messung bzw. Berechnung des Füllstandes oder anderer mechanischer Daten einer elektrisch leitenden Flüssigkeit |
WO1993000573A1 (en) * | 1991-06-25 | 1993-01-07 | Endress & Hauser Gmbh & Co. | Interface level detector |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3443438A (en) * | 1967-02-10 | 1969-05-13 | Robert Edgar Martin | Fluid indicating apparatus |
DE2728283C2 (de) * | 1977-06-23 | 1982-04-29 | Siemens AG, 1000 Berlin und 8000 München | Vorrichtung zur Überwachung des Tintenvorrates in Tintenschreibeinrichtungen |
US4382382A (en) * | 1979-11-01 | 1983-05-10 | General Electric Company | Multilevel liquid sensing system |
DE3115776A1 (de) * | 1981-04-18 | 1983-01-05 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Thermoelektrische fuellstandsmesseinrichtung |
GB8412461D0 (en) * | 1984-05-16 | 1984-06-20 | Schlumberger Electronics Uk | Fluid level measurement system |
US4720997A (en) * | 1986-12-01 | 1988-01-26 | Doak Roni K | Material level monitor |
DE3737607A1 (de) * | 1987-11-05 | 1989-05-24 | Hoefelmayr Bio Melktech | Verfahren und vorrichtung zur durchfuehrung von messungen an einer schaeumenden fluessigkeit |
US4903530A (en) * | 1988-12-08 | 1990-02-27 | Hull Harold L | Liquid level sensing system |
JP2570677B2 (ja) * | 1990-05-08 | 1997-01-08 | 株式会社村田製作所 | 液量計 |
-
1993
- 1993-05-29 GB GB939311187A patent/GB9311187D0/en active Pending
-
1994
- 1994-04-22 ES ES94302877T patent/ES2148287T3/es not_active Expired - Lifetime
- 1994-04-22 DE DE69425301T patent/DE69425301T2/de not_active Expired - Lifetime
- 1994-04-22 EP EP94302877A patent/EP0627615B1/de not_active Expired - Lifetime
- 1994-05-05 GB GB9408881A patent/GB2278448B/en not_active Expired - Fee Related
- 1994-05-06 IN IN379MA1994 patent/IN184470B/en unknown
- 1994-05-20 JP JP6106887A patent/JPH06347307A/ja active Pending
- 1994-05-25 CA CA002124299A patent/CA2124299C/en not_active Expired - Fee Related
- 1994-05-27 US US08/250,007 patent/US5553494A/en not_active Expired - Lifetime
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1056032A (en) * | 1964-04-08 | 1967-01-25 | Central Electr Generat Board | Improvements in or relating to fluid indicating apparatus |
US3370466A (en) * | 1965-09-24 | 1968-02-27 | United States Steel Corp | Method and apparatus for locating interfaces between fluids |
US4020488A (en) * | 1972-05-10 | 1977-04-26 | Robert Edgar Martin | Alarm and/or control apparatus |
US4371790A (en) * | 1980-09-19 | 1983-02-01 | Rmr Systems, Inc. | Fluid measuring system |
EP0447810A2 (de) * | 1990-03-07 | 1991-09-25 | Hl Planartechnik Gmbh | Elektrische Messanordnung zur Messung bzw. Berechnung des Füllstandes oder anderer mechanischer Daten einer elektrisch leitenden Flüssigkeit |
WO1993000573A1 (en) * | 1991-06-25 | 1993-01-07 | Endress & Hauser Gmbh & Co. | Interface level detector |
Non-Patent Citations (1)
Title |
---|
K.R.WALTON: "Sensor for the Measurement of the Level and Volume of Conductive Liquids", REVIEW OF SCIENTIFIC INSTRUMENTS, vol. 51, no. 4, April 1980 (1980-04-01), NEW YORK US, pages 504 - 508 * |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1998006105A1 (en) * | 1996-08-01 | 1998-02-12 | Combustion Engineering, Inc. | Fluid level measuring instrument for a nuclear power plant |
US5881117A (en) * | 1996-08-01 | 1999-03-09 | Combustion Engineering, Inc. | Mid-loop fluid level measuring instrument for a nuclear power plant |
ES2124175A1 (es) * | 1996-10-04 | 1999-01-16 | Gaggia Espanola | Procedimiento para controlar el nivel de un deposito de suministro de agua y dispositivo para su puesta en practica. |
EP0887628A1 (de) * | 1997-06-27 | 1998-12-30 | Solartron Group Limited | Sicherheitseinrichtung |
US6118190A (en) * | 1997-06-27 | 2000-09-12 | Solartron Group Limited | Fail-safe system |
US8532244B2 (en) | 2007-06-14 | 2013-09-10 | General Electric Company | System and method for determining coolant level and flow velocity in a nuclear reactor |
Also Published As
Publication number | Publication date |
---|---|
GB9408881D0 (en) | 1994-06-22 |
GB2278448B (en) | 1997-04-23 |
IN184470B (de) | 2000-08-26 |
CA2124299A1 (en) | 1994-11-30 |
GB9311187D0 (en) | 1993-07-14 |
CA2124299C (en) | 2005-03-15 |
US5553494A (en) | 1996-09-10 |
GB2278448A (en) | 1994-11-30 |
ES2148287T3 (es) | 2000-10-16 |
DE69425301D1 (de) | 2000-08-24 |
JPH06347307A (ja) | 1994-12-22 |
EP0627615B1 (de) | 2000-07-19 |
DE69425301T2 (de) | 2000-11-30 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP0627615B1 (de) | Füllstandsmessystem | |
EP0618428B1 (de) | Flüssigkeitsniveau Fühlsysteme | |
US6457355B1 (en) | Level sensing | |
US5103368A (en) | Capacitive fluid level sensor | |
CA2950965C (en) | Method and apparatus for monitoring fill level of a medium in a container | |
CA1045228A (en) | Liquid level gauging apparatus | |
AU644929B2 (en) | Computerized remote resistance measurement system with fault detection | |
CN1547660A (zh) | 组合液体状况监测器和液位传感器 | |
EP0534654A2 (de) | Wasserstandsmessung mit Hochfrequenzwellen | |
JPS6144324A (ja) | 流体レベル測定装置 | |
CA1038059A (en) | Liquid level gauging apparatus | |
EP0149279B1 (de) | Pegelmesser | |
GB2074325A (en) | Level Indicators for Electrically Conductive Liquids or Loose Materials | |
US3283577A (en) | Divided capacitance probe level gauge | |
US4007636A (en) | Liquid metal level indicator | |
US5247833A (en) | Water level measuring apparatus | |
US5860316A (en) | Capacitance probe | |
CN101784797A (zh) | 用于控制位于泵上游的容器内的材料柱高度的方法和设备 | |
WO2000043735A2 (en) | Method and apparatus for measuring fluid levels in vessels | |
CA2054490C (en) | Particle level sensor | |
JP3367168B2 (ja) | レベル測定方法及びレベル測定器 | |
PL197389B1 (pl) | Układ przetwornika pomiarowego dla czujników stanu napełnienia | |
JP3559098B2 (ja) | 液面測定装置 | |
SU717550A1 (ru) | Дискретный уровнемер | |
GB2354585A (en) | Apparatus for sensing the level of a fluid in a container |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): BE DE ES IT NL |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: SOLARTRON GROUP LIMITED |
|
17P | Request for examination filed |
Effective date: 19950607 |
|
RAP3 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: SOLARTRON GROUP LIMITED |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
17Q | First examination report despatched |
Effective date: 19990812 |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): BE DE ES IT NL |
|
ITF | It: translation for a ep patent filed |
Owner name: BARZANO' E ZANARDO MILANO S.P.A. |
|
REF | Corresponds to: |
Ref document number: 69425301 Country of ref document: DE Date of ref document: 20000824 |
|
REG | Reference to a national code |
Ref country code: ES Ref legal event code: FG2A Ref document number: 2148287 Country of ref document: ES Kind code of ref document: T3 |
|
EN | Fr: translation not filed | ||
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
NLS | Nl: assignments of ep-patents |
Owner name: SOLARTRON MOBREY LIMITED |
|
NLT1 | Nl: modifications of names registered in virtue of documents presented to the patent office pursuant to art. 16 a, paragraph 1 |
Owner name: WESTON AEROSPACE (2003) LIMITED Owner name: SOLARTRON LIMITED |
|
REG | Reference to a national code |
Ref country code: ES Ref legal event code: PC2A |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: BE Payment date: 20120426 Year of fee payment: 19 Ref country code: DE Payment date: 20120427 Year of fee payment: 19 Ref country code: NL Payment date: 20120426 Year of fee payment: 19 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: IT Payment date: 20120424 Year of fee payment: 19 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: ES Payment date: 20120426 Year of fee payment: 19 |
|
BERE | Be: lapsed |
Owner name: *SOLARTON MOBREY LTD Effective date: 20130430 |
|
REG | Reference to a national code |
Ref country code: NL Ref legal event code: V1 Effective date: 20131101 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: BE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20130430 Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20131101 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R119 Ref document number: 69425301 Country of ref document: DE Effective date: 20131101 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20131101 Ref country code: IT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20130422 |
|
REG | Reference to a national code |
Ref country code: ES Ref legal event code: FD2A Effective date: 20140610 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: ES Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20130423 |